The Reductions of Bis(terpyridyl) and Ethylenediaminetetraacetato Complexes of Cobalt(III) by Ascorbic Acid

The reductions of Co(terpy)₂³⁺ and Co(edta)^? complexes by ascorbic acid have been subjected to a detailed kinetic study in the range of pH =1–10.9. For each complex the rate law of the reaction is interpreted as a rate determining reaction between Co(III) complex and the ascorbic acid in the form of HA^? (k₁) and A^2? (k₂), depending on the pH of the solution, followed by a rapid scavenge of the ascorbic acid radicals by Co(III) complex. With given Ka₁ and Ka₂, the rate constants are k₁ = 0.25 and 9.87 × 10^?5 M^?1s^?1, k₂ = 1.28 × 10⁶ and 18.7 M^?1s^?1 for Co(terpy₎2³⁺and Co(edta)^? complexes, respectively, at T = 25 °C and μ = 0.50M (terpy)and 1.0 M (edta) HClO₄/LiClO₄. The mechanism of the reaction is discussed on the basis of Marcus theory for outer sphere electron transfer process. Spin change and charge effect, duly considered, account for the non‐adiabatic behavior in the reduction of Co(edta)^? complex.     

Heteroligand Cobalt(III) Complexes with Triethanolamine and Aminoacetic Acid

Heteroligand cobalt(III) chelates with triethanolamine and glycine, [Co(HTetm)GlyH₂O] · 2H₂O (I) and [Co(HTetm)GlyNH₃] · 2H₂O (II) (H₃Tetm is N(C₂H₄OH)₃ and HGly is glycine), were synthesized. The acidity constants of complex I were determined at an ionic strength of 0.1. The reactions of I with alcoholic solutions of acids, ammonia, and ammonium nitrate were studied. Binuclear complexes were obtained upon the interaction of I and II with CoCl₂ · 6H₂O. The complexes were characterized using UV–VIS (in aqueous and alcoholic solutions) and IR (in the solid state) spectroscopy. The ¹³C NMR spectra of solutions of Iand II were recorded. The plausible structures of the complexes are discussed.     

Structural Studies of Bis(cyclopentadienyl)molybdenum‐Amino Acid Complexes

The crystal structures of molybdocene‐amino acid compounds of the type [Cp₂Mo^IV(κN, κO‐AA)]⁺Cl^—·xH₂O with AA = D ‐phenylalaninato (x = 1.5), DL ‐leucinato (x = 2) and DL ‐valinato (x = 1) have been determined (Cp = η⁵‐C₅H₅). The compounds feature an almost planar, five‐membered chelate ring of the aminocarboxylate moiety (deprotonated amino acid) with the molybdenum atom. In the phenylalaninato complex π‐stacking between the phenyl rings is found. The complexes were proven kinetically stable at pH < 1 for at least 24 h.     

Sulfitoamine Complexes of Cobalt(III)

Abstract

Monosulfito and bis(hydrogensulfito) cobalt(III) complexes were prepared using sodium sulfite and sodium metabisulfite salts respectively. The two types of products showed different and characterizing patterns of IR and UV-visible spectra. They both contain Co-SO₃ linkages and the sulfite groups have similar or different site symmetries in the same compound.     

Reversed Phase Liquid Chromatographic Separation of Lysergic Acid Diethylamide (LSD) and Lysergic Acid Methylpropylamide (LAMPA)

Abstract

A fast and convenient procedure is described for the HPLC separation of LSD and LAMPA. These compounds are separated by a reversed phase (C18) procedure using a binary solvent system of methanol and pH 3 phosphate buffer. Under these conditions all compounds are eluted in a retention volume of 27 mL or less. This procedure allows a forensic sample to be identified as LSD and to eliminate LAMPA as a possibility.     

向日葵仁中绿原酸和咖啡酸的反相高效液相色谱法测定

建立了同时测定向日葵仁中绿原酸和咖啡酸的反相高效液相色谱法 ;采用美国Alltech公司的ALLTIMAC18 柱(250mm×4.6mmID,5μm) ,流动相为乙腈 -2 %(φ)乙酸溶液 (体积比15∶85) ,流速为1.0mL/min ,紫外检测波长327nm ;向日葵仁中绿原酸(chlorogenicacid)和咖啡酸(caffeicacid)在18min内得到很好的分离 ,该法简便、快速、结果准确、重复性好。     

Metallosupramolecular Architectures of Ambivergent Bis(Amino Acid) Biphenyldiimides

The metallosupramolecular chemistry of two enantiopure dicarboxylate ligands has been explored for their potential to form discrete or polymeric interlocked motifs. Consequently, both discrete and polymeric supramolecular complexes have been synthesised, yielding M₂L₂ metallomacrocycles ( 1 and 2 ), a heteroleptic M₂L₃ metallomacrobicycle ( 3 ), a non‐interpenetrated coordination polymer ( 4 ), and highly unusual chiral M₈L₈ squares ( 5 and 6 ). There appears to be a preference for the ligands to form M₂L₂‐type metallomacrocyclic structural units (which feature in 1 – 4 ), although these do not engage in any mechanical interlocking, which is perhaps a combined function of the ligand flexibility and relatively small pi‐surface contrasted to previous analogues. Using copper paddlewheel SBUs, chiral double‐walled squares ( 5 and 6 ) are formed with large internal cavities yet poor stabilities, unexpectedly featuring the paddlewheel motifs at the vertices of the polygonal complex.     

Cobalt(III) Complexes of D‐Galactosylamine

The β‐pyranose isomer of D ‐galactosylamine ( 1 ) formed complexes with three different cobalt(III) fragments. Crystals containing the dication [Co(tren)(β‐D ‐Galp1N2H_–1‐κ²N¹,O²)]²⁺ ( 3 ) showed coordination through the anomeric amino group (N1) and the deprotonated hydroxy group (O2) of the ⁴C₁ β‐pyranose form, which is also the major isomer of free galactosylamine. The cationic complexes [Co(fac‐dien)(β‐D ‐Galp1N2H_–1‐κ²N¹,O²)]²⁺ ( 4 ) and [Co(phen)₂(β‐D ‐Galp1N2H_–1‐κ²N¹,O²)]²⁺ ( 5 ) were analysed by NMR spectroscopy and showed the same coordination mode as 3 . In terms of available ligand isomers it was shown that 1 exhibits an anomeric equilibrium in solution of both pyranose and both furanose forms as is typical for the parent glycose, galactose.     

反相高效液相色谱法测定牙膏中的甘草次酸

采用反相高效液相色谱法测定了牙膏中的甘草次酸。在ＹＷＧ Ｃ１８（４０ｍｍｉ．ｄ．×２５０ｍｍ,１０μｍ）色谱柱上,以Ｖ（甲醇）∶Ｖ（００１ｍｏｌ／ＬＫＨ２ＰＯ４）＝８５∶１５（ｐＨ３０）的溶液为流动相,流速为１０ｍＬ／ｍｉｎ,紫外检测波长为２５４ｎｍ,室温下检测。甘草次酸用甲醇提取。甘草次酸的平均回收率为９９６１％～１０１６７％,样品测试相对标准偏差为１８５％～３１６％。方法操作简便、快速和准确。     

正反相模式下键合纤维素手性固定相对手性化合物的拆分

在自行合成的键合型纤维素-(3,5-二甲基苯基氨基甲酸酯)(CDMPC-CSP)手性固定相上,在正相模式下对苯偶姻和甲霜灵外消旋体进行了拆分,考察了流动相中醇以及温度在手性识别中对手性分离的影响。同时考察了反相模式下外消旋体的拆分。     

两个由5-硝基间苯二甲酸和双咪唑基配体构筑的锰、钴配合物的合成及晶体结构

通过水热法合成了2个新的配合物[Mn(NIPH)(mbix)]_n (1)和[Co(NIPH)(mbix)(H₂O)₃]_2n·2nH₂O (2)(H₂NIPH=5-硝基间苯二甲酸,mbix=1,3-双(咪唑基-1-基)苯)。并对其进行了元素分析、红外光谱、紫外光谱、热重和X-射线单晶衍射测定。这两个配合物通过氢键和π-π相互作用形成了三维超分子网状结构。     

2-(2-噻唑偶氮)-对-甲酚螯合物反相高效液相色谱同時分离测定镍、钴的研究——合金中微量钴和镍的测定

本文研究了2-(2-噻唑偶氮)-对-甲酚(TAC)与镍(Ⅱ)、钴(Ⅱ)螯合物的柱前衍生条件和液相色谱的分离条件。于KYWG-C_(18)柱上,用含有0.03mol/L KH_2PO_4-Na_2HPO_4(pH7.77)和2.5×10~(-4)mol/L TAC的甲醇-四氢呋喃-水(40∶10∶50 V/V)混合液为流动相,流速为1.0mL/min。于580nm处检测。该法用于四种标准合金中镍和钴的测定,回收率在98%～101.5%之间。Ni(Ⅱ)和Co(Ⅱ)的检出限(信噪比为2∶1)分别为0.2ng和1.5ng。建立了同时测定镍,钴的高灵敏、高选择性,快速的HPLC-光度法。     

Unnatural Amino Acid Synthesis Enabled by the Regioselective Cobalt(III)‐Catalyzed Intermolecular Carboamination of Alkenes

Herein, we report an unprecedented regioselective and entirely atom‐economic cobalt(III)‐catalyzed method for the non‐annulative, intermolecular carboamination of alkenes. The methodology enables the direct synthesis of unnatural amino acid derivatives and proceeds under redox‐neutral conditions with a completely regioselective C?C bond and C?N bond formation. Furthermore, this reaction exemplifies the inherently different mechanistic behavior of the Cp*Co^III catalyst and its Cp*Rh^III counterpart, especially towards β‐H‐elimination.     

Synthesis,Spectroscopic and X-ray Structural Study of cis-diazidobis- (ethylenediamine)Cobalt(III) Thiocyanate

Reaction of cis-diazidobis(ethylenediamine)cobalt(III)nitrate with ammonium thiocyanate in a 1?:?2 molar ratio in aqueous medium gave the title cobalt(III) compound, cis-[Co(en)₂(N₃)₂]SCN, as reddish brown crystals in almost quantitative yield. The complex salt was characterized by elemental analysis, IR, electronic, ¹H and ¹³C NMR spectroscopic studies. An X-ray structure determination revealed an ionic structure with the monoclinic space group P2₁/c, having cell dimensions a = 12.1950(6), b = 9.0317(5), c = 12.6017(7)?Å; β = 113.419(1)°, V = 1273.63(12)?ų and Z = 4. The structure was refined by a full-matrix least-square procedures to R ₁ = 0.0297 and wR ₂ = 0.0697.     

Partial Molar Volumes of Cobalt(III) Complexes. Part 3: Homologous Series of Aminopentaamminecobalt(III) Complexes

Partial molar volumes (V ₂°) have been determined at infinite dilution in aqueous solution at 20 °C for a series of octahedral N₆-coordinated cobalt(III) species having five-coordinated ammonia ligands along with an N-coordinated linear alkyl amine whose alkyl chain was varied from ethylamine to octylamine. The experimental values for V ₂° are consistent with the relative sizes of the ligands but show increasing deviations from those predicted by computer modeling, as the size of the cation increases, presumably due to the void space of the cation that increases with the size of the amine ligand. The value of the partial molar volume at infinite dilution increased by about 16 mL⋅mol⁻¹ with each added methylene group.     

Rhodium(III), palladium(II) and platinum(II) complexes of Bis(o-aminobenzenesulfonyl)ethylenediamine

New complexes of the formulae K₃[RhL ₃]·2 H₂O, [PdL]·H₂O and [M(LH₂)Cl₂] [whereM = Pd, Pt andLH₂ = bis(o-aminobenzenesulfonyl)ethylenediamine] have been prepared and characterized by conductivity measurements, thermogravimetric analysis, X-ray powder patterns and IR, Ligand Field and¹H-NMR spectroscopy.

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Rhodium(III), Palladium(II)- und Platin(II)-Komplexe mit Bis(o-aminobenzolosulfonyl)ethylendiamin (Kurze Mitteilung)

Zusammenfassung Neue Komplexe der allgemeinen Formeln K₃[RhL ₃]·2H₂O, [PdL]·H₂O und [M(LH₂)Cl₂] mitM = Pd, Pt undLH₂ = Bis(o-aminobenzolosulfonyl)ethylendiamin wurden dargestellt und mit Konduktionsmessungen, thermogravimetrischen Analysen, Röntgenstrukturanalysen, IR, Ligandfeld- und¹H-NMR-Spektroskopie charakterisiert.

     

Controlled Radical Polymerization Mediated by Amine–Bis(phenolate) Iron(III) Complexes

Tetradentate amine–bis(phenolate) iron(III) halide complexes containing chloro substituents on the aromatic ring are extremely efficient catalysts for controlled radical polymerization. Molecular weights are in good agreement with theoretical values and polydispersity indexes (PDIs) are as low as 1.11 for styrene and methyl methacrylate polymerizations. Complexes containing alkyl substituents on the aromatic ring are less efficient. Kinetic data reveal activity for styrene polymerization among the fastest reported to date and initial studies implicate a multimechanism system. Despite the highly colored polymerization media, simple work‐up procedures yield pure white polymers.     

Studies on Cobalt(III) Metallosurfactants. Kinetics and Mechanism of Reduction of Cobalt(III) by Iron(II) in Aqueous Acid Medium

The kinetics and mechanism of reduction of the surfactant complex ions, cis-chloro/bromo(dodecylamine)(triethylenetetramine)cobalt(III) by iron(II) in aqueous solution were studied at 303, 308 and 313 K by spectrophotometry under pseudo-first-order conditions using an excess of the reductant. The second-order rate constant increases with cobalt(III) concentration and the presence of aggregation of the complex itself alters the reaction rate. The reductions are acid-independent in the range [H⁺] = 0.05–0.25 mol dm⁻³. Variation of ionic strength (μ) influences the reaction rate. Activation and thermodynamic parameters have been computed. It is suggested that the reaction of Fe²⁺(aq) with the cobalt(III) complex proceeds by an inner-sphere mechanism. The critical micelle concentration (CMC) values of these surfactant metal complexes in aqueous solution were obtained from conductance measurements. Specific conductivity data (at 303, 308 and 313 K) served for the evaluation of the temperature-dependent CMC and the standard Gibbs energy of micellization (ΔG_m⁰).